Source: Justin McCarthy, "Americans Still Greatly Overestimate U.S. Gay Population", 27 June 2019.
A poll in 2017 found 4.5% of the United States population identifies itself as lesbian, gay, bisexual or transgender. But notice that this lumps a lot of people together with different sexual practices.
Source: Statista Research Department, "U.S. Homosexuality - Statistics & Facts", 9 June 2017.
Another survey found that 2.2% of the adult male population claims to be homosexual and 1.1% of the adult women population claims to be lesbian. Assuming that half the population is male and half female, then actual homosexuals only make up 1.6% of the total population. The remaining 2.9% would be those who don't care who they have sex with and those who claim to be transgender.
The number might actually be less because I don't know how many actually have had sex with the same gender. There are many people who are convinced that they are homosexual yet have never had sex with a person of the same gender.